A design for an electromagnetic filter for precision energy measurements at the tritium endpoint

M. G. Betti, M. Biasotti, A. Boscá, F. Calle, J. Carabe-Lopez, G. Cavoto, C. Chang, W. Chung, A. G. Cocco, A. P. Colijn, J. Conrad, N. D'Ambrosio, P. F. de Salas, M. Faverzani, A. Ferella, E. Ferri, P. Garcia-Abia, G. Garcia Gomez-Tejedor, S. Gariazzo, F. GattiC. Gentile, A. Giachero, J. E. Gudmundsson, Y. Hochberg, Y. Kahn, M. Lisanti, C. Mancini-Terracciano, G. Mangano, L. E. Marcucci, C. Mariani, J. Martínez, M. Messina, A. Molinero-Vela, E. Monticone, A. Nucciotti, F. Pandolfi, S. Pastor, J. Pedrós, C. Pérez de los Heros, O. Pisanti, A. D. Polosa, A. Puiu, Y. Raitses, M. Rajteri, N. Rossi, R. Santorelli, K. Schaeffner, C. F. Strid, C. G. Tully, F. Zhao, K. M. Zurek

Research output: Contribution to journalReview articlepeer-review


We present a detailed description of the electromagnetic filter for the PTOLEMY project to directly detect the Cosmic Neutrino Background (CNB). Starting with an initial estimate for the orbital magnetic moment, the higher-order drift process of E×B is configured to balance the gradient-B drift motion of the electron in such a way as to guide the trajectory into the standing voltage potential along the mid-plane of the filter. As a function of drift distance along the length of the filter, the filter zooms in with exponentially increasing precision on the transverse velocity component of the electron kinetic energy. This yields a linear dimension for the total filter length that is exceptionally compact compared to previous techniques for electromagnetic filtering. The parallel velocity component of the electron kinetic energy oscillates in an electrostatic harmonic trap as the electron drifts along the length of the filter. An analysis of the phase-space volume conservation validates the expected behavior of the filter from the adiabatic invariance of the orbital magnetic moment and energy conservation following Liouville's theorem for Hamiltonian systems.

Original languageAmerican English
Pages (from-to)120-131
Number of pages12
JournalProgress in Particle and Nuclear Physics
StatePublished - May 2019


  • CNB
  • Cosmic Neutrino Background
  • Neutrino mass
  • Relic neutrino
  • Transverse drift filter

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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